MeV Proton Irradiation Damage on Tungsten - Blisters Formation

Radiation damage from proton irradiation exhibits specific features due to the retention of hydrogen in the metal, such as, hydride formation, embrittlement and nucleation and growth of hydrogen blisters. Over the last two decades, proton radiation damage in tungsten and its alloys has been of increased interest, due to the choice of tungsten as a plasma facing material in nuclear fusion systems,and as a target material in accelerators, exposing it to low energy proton plasma, high temperatures and high energy ions.

The material response of tungsten to irradiation by MeV protons has been studied experimentally, in particular with respect to bubble and blister formation. Tungsten samples were irradiated by 2.2 MeV protons at the Soreq Applied Research Accelerator Facility (SARAF) to doses of the order of 1017protons/cm2 which are below the reported critical threshold for blister formation derived from keV range irradiation studies. Large, well-developed blisters are observed indicating that for MeV range protons the critical threshold is at least an order of magnitude lower than the lowest value reported previously.

The effects of flounce, flux, and corresponding temperature on the distribution and characteristics of the obtained blisters were studied. In order to study the effect of flux and temperature , cooled target cell was designed and built. Further characterization of FIB cross sections of several blisters exposed their depth and structure.